As known to those skilled in the art, various Quality of Service (“QoS”) parameters may be defined by a user for each virtual path connection (“VPC”) or virtual channel connection (“VCC”) in an ATM network. The QoS parameters are defined on an end-to-end (i.e. system-wide) basis and may include, for example, cell delay variation (“CDV”), maximum cell transfer delay (“CTD”), cell loss ratio (“CLR”), cell error ratio (“CER”), severely errored cell block ratio (“SECBR”) and cell misinsertion rate (“CMR”). A set or a subset of these various QoS parameters may define a QoS of a VPC or VCC and determines the relative priority accorded to traffic on the VPC or VCC.
In a heterogeneous network including an ATM network, in order to maintain efficient traffic flow from the ATM network to an adjacent or intermediary network and vice versa, it is necessary to effectively manage traffic at switches connecting the networks. It may be that, at a given switch connecting an ATM network to an adjacent network, the allotted ingress bandwidth for traffic having a given QoS exceeds the available egress bandwidth for that QoS. In this case, the switch may become a traffic congestion point. As will be appreciated, effective management of potential traffic congestion points will affect the overall performance of the heterogeneous network.
Heretofore, various systems have been proposed for providing mediation at a switching point in a heterogeneous network. Use of multiple priority queues has been attempted, but use of back-pressuring signals only for traffic management has provided only limited improvement. Also, while one-to-one correspondence between each class of ingress connection and each class of egress connection has been attempted for relatively small networks, this one-to-one mapping scheme quickly becomes unworkable as the number of connections grows.
Therefore, what is needed is a new and effective method and system for mediating traffic between an ATM network and an adjacent network in a heterogeneous network environment.